Help with port settings on a 3750

[james.metcalfe]

We've got a number of 3750 switches across our network and at our colo. These switches are a mix of 24 and 48 port, some FE and some GiB, most are stacked but a few use a X-over cable. My question is, what's the best settings for the devices we have connected. It's mostly setup default so PortFast is disabled, and most everything is Auto but I feel these things should be set for better performance.

These are the devices we have connected, if you can tell me the recommended settings for peak performance I would greatly appreciate it.

2003 & 2008 stand alone servers

2012 Hyper-V host servers

Cisco Wireless Lan controller

switches connected via X-over cables

Sonicwall firewall

Example: 2012 Hyper-V servers - static max duplex, static max speed, Port Fast enabled, flow control Receive off, Send N/A, Auto MDIX On

Also, I've read about the Spanning Tree can have some performance effects...what's the best want to set it correctly?

Thanks

James

[Leo Laohoo]

Catalyst switches connected with VM servers can have some bad effects if you don't have QoS enabled.  This is due to the inherit capabilities of VM servers if they transfer continuous traffic to the switch and the switch's buffer gets overwhelm (and when the data buffer overflows, the switch will start dropping packets).  

[james.metcalfe]

Thanks for that info Leo. Is this just a matter of enabling QoS or are there certain parameters that also need to be set? Is this something that's set for the entire switch or just individuate ports?

Thanks,

James

[Leo Laohoo]

Also, I get a notification in the lower right about SmartPorts not being set, or something to that nature. Is this something I should be concerned about?

Someone must've enable Auto SmartPort (aka ASP) globally.  Should you be of concern?  Depends.  ASP has NO PLACE in the DC.  Only you will know why ASP is enabled on a DC switch. 

Is this just a matter of enabling QoS or are there certain parameters that also need to be set? 

I'd like to call QoS as "black magic".  QoS is not a universal setting:  It's not a setting where everyone and anyone can use.  You need to customize your settings and it takes a few times/attempts to get the settings right down.  Hence, why I call it "black magic".  There are only a few people in this forum who are good at QoS settings.  Look for a Cisco VIP guy named Joseph.  If he's not busy he should pop up (hopefully not in a cloud of dark smoke and/or over a pentagram surrounded by black candles [JOKE]).

Long term, you need to look into Cisco Nexus range of switches as this range of switches are tailored/designed to work in a DC environment.  Nexus is able to handle the continuous data traffic from VM machines.  Joseph also recommends the Catalyst 4500-X as a cheaper alternative as he's had experience deploying the 4500-X in a DC (as well as making QoS fine tuning on lower-end Catalyst switches like the 3560/3750).

[james.metcalfe]

Thanks Leo, I'm going to have to track down this infamous Joseph and see if he can help get me going in the right direction. I did check the switches and all the stacks have QoS enabled but there's nothing really configured. We don't have budget for a 4500 so I just need to get the 3750's working as best they can in our environment.

Thanks,

James

[james.metcalfe]

Also, I get a notification in the lower right about SmartPorts not being set, or something to that nature. Is this something I should be concerned about?

Thanks